APPLICANT'S ABSTRACT: The overall aim of this proposal is to study alcohol induced aggression and attempt to determine the underlying neurochemistry of this behavior. Specific Aims: 1. To measure alcohol induced aggressive responding in subjects with Antisocial Personality Disorder (ASP and matched controls 2. To measure baseline serotonin function in subjects with ASP and matched controls using an ipsapiron neuroendocrine challenge. 3. To measure changes in alcohol induced aggressive responding in subjects with ASP after chronic administration of the serotonin reuptake inhibitor paroxetine compared to placebo. Rationale: The association between ethanol use and violence in the general population has been well documented (Lowenstein et al., 1990, Macdonald, 1961). Ethanol also increases aggressive responding in humans and animals under controlled laboratory conditions, but large inter-individual differences in this effect have been observed (Cherek et al., 1 984, Miczek et al., 1 993) Retrospective studies which examine the relationship between ethanol use and aggression find that alcoholics with Antisocial Personality Disorder (ASP) have an earlier age of onset of drinking, and more social and occupational problems related to drinking (Hesselbrock et al., 1984, Schuckit et al., 1985). These individuals have been found to have lower serotonin (5-HT) function as measured by CSF 5HIAA (Virkkunen et al., 1994). Thus there is evidence linking ASP and 5-HT to aggression and ethanol. The research proposed will investigate the relationship between ASP and ethanol induced aggressive responding and attempt to determine the role of 5-HT in these behaviors under controlled laboratory conditions.